This invention pertains to the field of elevators, and in particular, to adjusting the steering angle of an elevator sheave during or after installation.
When flat ropes or belts pass over a sheave or shaft, they tend to move (xe2x80x9ctrackxe2x80x9d) across the sheave or shaft under certain conditions: (1) if the belt is not almost perfectly perpendicular to the shaft, or (2) if the belt has non-uniform properties across its cross-section. For example, the sanding belt of a belt sander moves across the shaft during use, necessitating an adjustment of the shaft to ensure perpendicularity between the sanding belt and the shaft. Another example is a VCR, which has a tracking control for the same purpose. If the lateral movement of the belt across the shaft is too great, the belt can track off the shaft and become damaged, tangled, or cut in two.
With the advent of belt-powered machinery during the early industrial age, it was discovered that making the belt with a slightly curved cross-section and imparting a slight curve (crown) to the shaft reduced tracking and limited horizontal belt movement to a small area. Thus, a region of stability exists as long as the angle between the belt and the shaft are close to 90 degrees, even if exact perpendicularity is not maintained.
In the case of an elevator using coated steel belts (CSB) instead of wire ropes, the shaft must be installed within the region of stability, and must be capable of being adjusted as needed throughout the life of the elevator.
Briefly stated, a steering angle of an elevator sheave on a shaft is adjusted at installation and subsequently during maintenance by one of several embodiments. In one embodiment, a bolt with a jam nut is adjusted to position the shaft precisely. In another embodiment, a tee bracket is anchored to a hoistway wall, and a jack bolt with shims is used to adjust the vertical placement of the long beams that support the elevator car frame and therefore the shaft.
According to an embodiment of the invention, an apparatus for adjusting a steering angle of an elevator sheave on a shaft includes retaining means for retaining the shaft in an elevator car frame; vertical positioning means for adjusting a vertical position of the shaft; and horizontal positioning means for adjusting a horizontal position of the shaft; whereby an axial direction of the shaft is adjusted to be substantially perpendicular to a gravitational force acting on the elevator car frame.
According to an embodiment of the invention, an apparatus for adjusting a steering angle of an elevator sheave on a shaft includes a retainer retaining the shaft in a first frame; a flat rope reeved over the sheave, the flat rope having an entry direction with respect to the sheave and an exit direction with respect to the sheave; and a first positioning device for adjusting a position of the shaft with respect to the entry direction of the flat rope, whereby an axial direction of the shaft is adjusted to be substantially orthogonal to the entry direction.